Back to EveryPatent.com
United States Patent | 5,619,242 |
Haneda ,   et al. | April 8, 1997 |
An image forming apparatus for forming an image on an image forming body by scanning a plurality of modulated laser beams is disclosed. The apparatus is provided with a generator to generate a plurality of reference signals each with a differrent phase from other reference signals, a detector for detecting the difference of image density between two adjacent image pixels, combined modulator to generate a modulated laser beam by combining a selected laser beam, a selected reference signal and the image density. The detector classifies each pixel as one of an edge starting pixel, an edge ending pixel, and a non-edge pixel based on the value of image density difference relative to positive and negative threshold values. The selection of the laser beam and the reference signal is based on the image density difference detected by the detector and the class of the pixel.
Inventors: | Haneda; Satoshi (Hachioji, JP); Fukuchi; Masakazu (Hachioji, JP); Miwa; Tadashi (Hachioji, JP) |
Assignee: | Konica Corporation (Tokyo, JP) |
Appl. No.: | 179818 |
Filed: | January 11, 1994 |
Jun 27, 1990[JP] | 2-169273 | |
Jul 16, 1990[JP] | 2-187487 |
Current U.S. Class: | 347/131; 358/300 |
Intern'l Class: | B41J 002/435; H04N 001/409 |
Field of Search: | 395/107,108,104,101 358/298,458,300 347/251,252,254,240,131,247,237,132 |
4245260 | Jan., 1981 | Doelves | 358/299. |
4253102 | Feb., 1981 | Kataoka et al. | 346/108. |
4347523 | Aug., 1982 | Ohara | 346/108. |
4393387 | Jul., 1983 | Kitamura | 346/108. |
4395766 | Jul., 1983 | Ohnishi et al. | 358/298. |
4594596 | Jun., 1986 | Takahashi et al. | 346/108. |
4626923 | Dec., 1986 | Yoshida | 358/298. |
4679057 | Jul., 1987 | Hanada | 346/108. |
4788560 | Nov., 1988 | Miura | 346/108. |
4812861 | Mar., 1989 | Sasaki et al. | 346/108. |
4831392 | May., 1989 | Dei | 346/154. |
4847641 | Jul., 1989 | Twig | 346/154. |
4864326 | Sep., 1989 | Kawamura et al. | 346/108. |
4868684 | Sep., 1989 | Suzuki | 358/458. |
4967284 | Oct., 1990 | Yoshida et al. | 346/108. |
4978849 | Dec., 1990 | Goddard et al. | 346/108. |
5055943 | Oct., 1991 | Kishida | 358/458. |
5432611 | Jul., 1995 | Haneda et al. | 358/298. |